Compared with patients without the inflammatory condition, patients with diverticulitis had an adjusted 4.7-fold hazard of developing IBS (95% CI 1.6-14.0, P=0.006) over up to 9 years of follow-up, as well as 2.4-fold (95% CI 1.6-3.6, P<0.001) and 2.2-fold (95% CI 1.4-3.5, P<0.001) adjusted hazards for a functional bowel disorder or mood disorder, respectively, according to Brennan Spiegel, MD, of the West Los Angeles Veterans Affairs Medical Center in California, and colleagues.

"We propose calling this disorder post-diverticulitis IBS," which "appears to predispose patients to long-term gastrointestinal and emotional symptoms after resolution of inflammation ... similar to post-infectious IBS," they wrote in the December issue of Clinical Gastroenterology and Hepatology.

The authors noted that patients with diverticulosis also frequently present with IBS. However, recent research has shown that progression from diverticulosis to diverticulitis is rarer than previously thought, particularly among older patients with diverticulosis. In addition, surgical treatments for diverticulitis are expensive and risky.

To study the incidence of diverticulitis with IBS, functional bowel disorders, and mood disorders, the authors conducted a retrospective analysis of 1,102 patients with diverticulitis and 1,102 matched controls over a mean 6.3 years of follow-up.

Participants were treated at the Veterans Affairs Greater Los Angeles Healthcare System. Case patients met the definition of diverticulitis or its complications -- diverticular abscesses and diverticular perforations -- as given in the International Classification of Diseases, 9th revision (ICD-9), and had a formal chart diagnosis of the condition. These patients received a course of oral or parenteral antibiotics.

The primary outcome was a diagnosis of "post-diverticulitis IBS" based on a new IBS diagnosis following enrollment or an index diverticulitis attack. Secondary outcomes included presentation of related functional bowel diseases, such as spastic colon, functional diarrhea, constipation, and abdominal pain, as well as new diagnoses of depression and related mood disorders based on ICD-9 criteria.

From baseline, there were 24 new cases of IBS, including 20 in the diverticulitis sample and four among controls. In addition, there were 146 new functional gastrointestinal diagnoses, including 95 in the cases and 51 in controls, as well as 98 new mood disorder diagnoses, including 63 case diagnoses and 35 control diagnoses.

The authors cautioned that "it is possible that diverticulitis patients in this study were simply misdiagnosed as having IBS, or vice versa," though they noted that the false negatives may be stymied by exclusion of those with pre-existing IBS and functional bowel diagnoses, as well as the presenting cases of mood disorders post-diverticulitis.

They also noted that the study did not prove that diverticulitis causes IBS, and that the study was limited by a low rate of IBS presentation in the sample overall.

The study was funded through a grant from Shire Pharmaceuticals.

The authors received support from Ironwood Pharmaceuticals, Prometheus, Takeda, Amgen, Ritter Pharmaceuticals, and Shire Pharmaceuticals.

Reviewed by Zalman S. Agus, MD Emeritus Professor, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner

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